Problem: What is the greatest common factor of $5$ and $6$ ? Another way to say this is: $\operatorname{gcf}(5, 6) = {?}$
The greatest common factor is the largest number that is a factor of both $5$ and $6$ The factors of $5$ are $1$ and $5$ The factors of $6$ are $1$ $2$ $3$ , and $6$ Thus, the greatest common factor of $5$ and $6$ is $1$. $\operatorname{gcf}(5, 6) = 1$